The present invention relates to an anisotropic conductive film. More particularly, the present invention relates to an anisotropic conductive film used to secure continuity of a semiconductor device during a functional test of the device, and to a test method for a semiconductor device using the film.
In recent years, further integration of integrated circuits has resulted in increased numbers of electrodes carried on a bear chip semiconductor device, which means the arrangement patterns thereof have become fine at narrower pitch. This in turn has resulted in increased costs for fabricating the device as well as a circuit board for mounting the device due to finer wiring patterns. A functional test of a semiconductor device, therefore, should be done before mounting the device on a circuit board. Otherwise, the device judged defective after mounting is discarded together with the good circuit board, thereby lowering the production efficiency of the circuit board while increasing an economical loss. The same applies to the case where the other one is defective.
For functional testing of a semiconductor device, therefore, it is desirable to run various functional tests prior to mounting the device on a circuit board. One of the methods therefor includes bringing a semiconductor device into contact with a circuit board via an anisotropic conductive film at the same position as in actual mounting, and running a functional test of the device.
The present inventors have closely examined the contact state during the test and found that bare chip semiconductor devices have warp, and the circuit boards have warp and waviness. As a result, many electrodes in one device fail to make an appropriate contact with the conductor part of the circuit board, which impairs the reliability of the test. To solve this problem, the contact load (pressure) may be increased. However, even if all the electrodes in the device and the conductor parts of the circuit board are connected, bump contacts formed on the electrodes of the device are deformed by the test itself.
When the semiconductor device that passed the test is mounted on a circuit board, therefore, the deformed bump contacts now cause a connection failure.
It is therefore an object of the present invention to solve the above-mentioned problems and provide a test method that enables a functional test with high connection reliability by applying a low contact load, even in the case of a semiconductor device having narrow pitch electrodes, as well as an anisotropic conductive film to be used therefor.
The present invention provides the following.
(1) A method for a functional test of a semiconductor device, comprising the steps of
(a) sandwiching an anisotropic conductive film between a semiconductor device and a circuit board and
(b) applying a contact load of 3-50 gf per one electrode of the device to achieve functionally testable conduction between the device and the board, the anisotropic conductive film comprising a film substrate made of an insulating resin and plural conductive paths having a total length of 60-500 xcexcm and made of a conductive material, and having a structure wherein the plural conductive paths penetrate the film substrate in the thickness direction and protrude from the both surfaces of the film substrate, which paths being insulated from each other, wherein the film as a whole has an elastic modulus of 0.1-1.0 GPa at 25-150xc2x0 C.
(2) The method of the above-mentioned (1), wherein the anisotropic conductive film deforms by 5-30 xcexcm due to the contact load.
(3) The method of the above-mentioned (1), wherein at least the conductive paths in the film substrate are metal conductor wires having a diameter of 5-30 xcexcm and the protrusion is either the metal conductor wire itself or a metal precipitated on an end of the metal conductor wire.
(4) An anisotropic conductive film for a functional test of a semiconductor device, which comprises a film substrate made of an insulating resin and plural conductive paths having a total length of 60-500 xcexcm and made of a conductive material, and which has a structure wherein the plural conductive paths penetrate the film substrate in the thickness direction and protrude from the both surfaces of the film substrate, which paths being insulated from each other, wherein the film as a whole has an elastic modulus of 0.1-1.0 GPa at 25-150xc2x0 C.
(5) The film of the above-mentioned (4), wherein at least the conductive paths in the film substrate are metal conductor wires having a diameter of 5-30 xcexcm and the protrusion is either the metal conductor wire itself or a metal precipitated on an end of the metal conductor wire.
(6) The film of the above-mentioned (4), wherein at least the conductive paths in the film substrate are covered with a layer made of a resin material other than the resin material of the film substrate.